In the present market, the design of the vehicular (automotive) headlamps may be characterized by fixed emitting fixtures presenting a fixed luminous intensity with unidirectional orientation of the main light rays (vectors). The photoelectric characteristics of these headlamps are controlled manually which in fact adds to the burden of night driving, increasing driver's response time to avoiding obstacles and reduces his perception in distinguishing shapes and the road topography due to the high contrast and penumbra effects created by such static design concepts. Due to the sudden change in road illumination intensity during high-low beam switching, there are seconds of blindness following this action which have negative results in driving performance and had proven to be a source of accidents. Prior art is basically oriented on limited initial illumination and relies on increasing the frontal and side luminosity accordingly with the external the light conditions, in other words it starts at the low point of illumination and adjusts it higher as needed.
This application introduces a new concept where initially all light emitting devices provide full frontal and side illumination over a wide angle of visibility pattern which is further controlled and adapted to respond to the exterior light conditions by diminishing the initial intensity and directional light parameters to lower levels.
Some more advanced designs include mechanized headlamps which respond to the driver's change of direction and improve the side and curve visibility and with variable intensity controls as presented in the following granted US patents; U.S. Pat. No. 7,950,837 B2—Yatsuda et al. May 2011, U.S. Pat. No. 7,815,352 B2—Naganawa et al. October 2010, U.S. Pat. No. 7,891,851 B2—Turhan, Alcelik Feb. 22, 2011, U.S. Pat. No. 6,504,265—Toda/2003, and U.S. Pat. No. 6,513,958—Ishikawa/2003.
Such headlamps are complex in their mechanical design, expensive to maintain or replace and have the main disadvantage of taking the front illumination and displacing it sideways which as result diminishes the forward illumination with unpredictable results. A view at the contemporary automotive control systems reveals that from navigation to brakes and many other driving functions or safety features are computer controlled while the vehicular illumination systems remain manually operated thus presenting a subjective rigid design with limited performance and presenting deficiencies which are no longer suitable for a modern vehicle. Novel systems are demanded by the market and in response a unique solution is presented in this application.
Prior art cited by the patents above are seeking an improved forward and side illumination pattern by using fixed or mobile light devices assembled on the same known planar surface and make use of electromechanical headlamp positioning systems or are using reflectors and light concentrators for directional lighting. Each system has its technological advantages which also encounters specific economical drawbacks.
The proposed application eliminates the need for mechanical actuation of the light emitting devices and proposes a three dimensional disposition of the light emitting devices (LEDs that could be supplemented by additional Laser devices) within the headlamp assembly which provides a wide spatial illumination. The herein system and method of illumination produces unconventional patterns of light with continuously adjusted parameters of intensity and direction. In other terms, this headlamp provides an initial full 2 PiSteradian of solid angle illumination in normal driving conditions in the absence of concomitant traffic and will adjust down its parameters to generate more restrictive patterns of illumination as it is determined by external illumination and traffic conditions, a concept nor perceived or anticipated by any of the prior art. Some prior art as in U.S. Pat. No. 8,080,942 Heider, is describing a dynamic, adaptive light control system of a planar construction comprising of supplemental light sources which are positioned at three different fixed angles and sharing location with a regular daytime running light module. It also presents a method of adaptive front lighting employing control techniques like device switching, PWM, dimming or other methods a priori existent in the public domain.
This application differentiates itself from these claims by bringing a novel and unobvious solutions by proposing a three-dimensional asymmetric principle of building a headlamp structure and by presenting a method of multidirectional light emission over a wide angle of view which automatically and continuously adapts its field of illumination in a multitude of overlapping patterns. Such geometrical structure is comprised of multiple polygonal shapes attached to a central polygonal shape at various and unequal angles. The upper facet shown in FIG. 3 makes an exception from this rule by having its angle of inclination oriented downward and forward for the purpose of creating the upper cut-off limit of illumination hence reducing the blinding effect to the incoming traffic and also reducing the glare created by dust, fog, rain, snow or other external conditions. Such design and method of illumination provides an economic design solution which is superior to technologies relying on an adjustable mirror-lens combination of elements arranged in various planar positions as described by the prior art.
The proposed physical design brings another original feature by including all the lighting required by a vehicle, within a single multifunctional embodiment which is using the same light emitting devices for multiple purposes by providing a continuously controlled low to high beam range of illumination, the signaling lights by changing the color spectrum of at least one of the existing LEDs and also provide position lights without raising the need for separate light devices or hardware.
The present application recognizes prior art elements in the pending application Ser. No. 12/422,284 which suggests its possible use in a vehicular illumination system. The concept of an asymmetric angular placement of various facets containing the light emitting devices is not presented in Ser. No. 12/422,284 which may not be foreseen as a possible method of automatic control or be presumed constructively as described in the present application.
Experimentation with various geometrical shapes and angle of distribution of the light emitted by LEDs and Laser sources lead to the conclusion that an asymmetric apparatus having a variable geometry that contains the emitting light sources positioned at predetermined angles produced a wide, uniform pattern of illumination. When individually controlled in intensity and direction, the combined light produced by the system created the best overall illumination patterns conforming with the vehicular illumination standards in effect.
Along with introducing the concept of angular displacement of the light sources in five or more directions of illumination ex., Up/Down/Left/Right and the Center for a selective directional emission of light rays, the herein application invokes an adaptive discrete control of light intensity and a switching algorithm of emitters, individually and in groups for an efficient electric power management and omnidirectional dispersion of light which can be selectively oriented. The light emitters assembled on the facets of the asymmetric geometrical structure are and spatially disposed as to generate a wide distribution of the light vectors and to emit a spatial diffuse light with multiple adaptive directional vector component patterns, and being under the control of a microprocessor or a plurality of microcontrollers. This form of light distribution allows the realization of a multidirectional radiant source, with variable luminous flux and illuminance, which is integrated over all the directions of a solid angle or 2π Steradians.
Having a radiometric analysis of the light emitting sources, the herein design saves electrical energy [Watt*Hour] thus increasing light efficacy through the emitters switching technique and through the PWM (Pulse Width Modulation) principles applied to each directional emitter-module (Left, Right, Up, Down and Center modules). From a photometric point of analysis the PWM controls the light intensity of each emitter-module and relies on the feedback signal delivered by the photo-sensors or cameras which in turn assures a maximum luminous intensity [lm] in the driving direction after compensating for the incoming traffic and surrounding light sources. In effect, such adaptive light control system is designed to minimize the glare while enhancing the quality of the allover illumination and therefore limiting the negative effects of the eye's difficulty to adapt to sudden light intensity changes.
This invention is focused on reducing drastic changes in the illumination levels (as encountered when changing from high beam to low beam) and produces constant illumination over the whole scene, issue not presently addressed by any of the headlamp devices. Illumination levels over the scene produced by traditional sources can contain either insufficient or over illuminated portions, phenomenon associated with a corresponding decrease in human reaction time due to the inertial effect on the eye receptors recovery called the after image effect. A much wider area of illumination provided by this design facilitates early detection of obstacles thus limiting the long term driving stress.
By controlling the left and right fields of illumination this design prevents the formation of direct glare (the presence of a bright light in the visual field) to the incoming traffic.
Some of the most important features of the present asymmetrical geometry concept applied to vehicle headlamps are; a) wide area of visibility over the shoulder and over curved roads without the aid of motion devices, b) elimination of the scotoma effect on the eye by extending the visibility in critical zones situated ahead and sideways.
Studies by Brebner and Welford, 1980 and Luce (1986) establish that the mean simple reaction (the acknowledgement of visual stimuli but without including a physical response time) is approximately 190 ms, while Eckner et all. (2010) determines it to be 268 ms. The average time calculated for the mean simple reaction from these studies is averaging at 229 ms, and it becomes even longer for images picked around the eye edges and at night time.
The human biological response time to light stimuli calculated from the moment of perception to the moment an image is created on the brain is called recognition reaction time and extends to approximately 384 ms, according to Eckner et. all study (2010).
If we consider that at the actual cruising speed of a vehicle is 65 MPH (or 104.6 Km/h) such vehicle will advance by a distance of 95.3 Ft (29.06 m/s) every second. Considering that the human recognition reaction time is approximately 384 ms (or 0.384 s), the distance the same vehicle will travel before the driver would have reacted to the visual stimuli is 36.59 Ft (11.15 m). This is equivalent with driving blind for 36.59 Ft, situation that could be only aggravated by a limited peripheral illumination delivered by the regular headlamp designs. An additional visual impediment is created by the fixed illumination field of the traditional headlamps which widely vary among manufacturers. Such negative effects are compensated for in this invention through the adoption of an adaptive illumination system that generates a wide view pattern which is selectively adjusted in intensity and direction without compromising luminosity via restrictive geometrical or optical methods.
The herein design addresses all the functional parameters of a vehicular headlamp and improves the overall visibility by producing five (in this application) or more independent adaptive illumination patterns, and extends the distance and angle of view through its automatic light intensity control which receives feedback from automotive ambient light sensors (ALS). The negative effects created by the time delayed human reaction is reduced in the herein design by constantly adjusting the forward and side illumination, hence allowing for early detection of obstacles which in turn results in a longer time to react and to higher road awareness with reduced driver fatigue. This invention proposes a multiple light emitting modules assembled on a number of geometrical facets of a headlamp, which facets are positioned at various angles measured from the center module/facet so that the light vectors (300) of the central module/facet are oriented forward, the Left and Right facets' vectors (200) are oriented sideways, and oriented downward for the Up and Down facets, as depicted in FIG. 8 (light vectors top view), and in FIG. 10 (light vectors side view).
This headlamp and signaling system relies on proprietary real-time microprocessor control routines, and a data acquisition unit running independent of the main vehicle computer and common interfacing is limited to displaying various functional states or malfunction of the illumination system on the vehicle monitor. A separate display monitor may be also provided for displaying the headlamp's operational status.
This concept of continuously adaptive lighting systems for vehicular applications originates with the necessity to increase the quality of illumination and to extend the field of visibility to approximately 2 Pi Steradians or even to full 4 Pi Steradians (a whole sphere) in special applications, having also the scope of eliminating spots of high intensity and penumbra and to provide a source of uniform illumination with wide spatial visibility and high detail throughout the whole scene under observation. The illumination pattern and intensity parameters of the headlamp are continuously controlled by a microprocessor/microcontroller system working to reduce the glare to the incoming traffic while enhancing the overall visibility.
The presented design may be integrated with other video electronic equipment employing high quality imaging applications as could be the case in 3-D viewing devices for commercial or military use.
The photo-sensors, video cameras, position encoders and accelerometers included in the system provide the input feedback signals for low/high beam lighting, for the directional pattern control of the emitted light rays without the necessity of any mechanical motion devices and also for the emitter color spectrum change.
In full operating mode, the area of illumination covers a solid angle of 2 Pi Sr. (2 Pi*Steradian), or an equivalent of 180° (planar Degrees) in a two dimension angular representation. During regular operation the luminous intensity and spatial coverage over a 2 Pi Sr., area is dynamically and continuously adjusted by electronic circuitry as it is dictated by the surrounding illumination characteristics. This new adaptive control concept when applied in vehicular headlamp design produces constant luminosity of the road ahead, reduces the eye strain while revealing a considerably improved view of details. The automatically controlled wide angle illumination pattern guarantees visibility around the curve prior to taking the turn without affecting the front visibility.
During the daytime use, the headlights are dimmed to a low level by the PWM (Pulse Width Modulation) signal applied to the LED's driver circuits upon comparing the environment light to a threshold which is electronically set and may be also manually adjusted.
The signaling for direction change is provided by the same emitter devices assembled on the left and right geometrical facets of the headlamp by changing their radiation spectrum to approximately 540 nm wavelength corresponding to a yellow/orange light, spectral change that may be also generated by choosing individual multi-pin colored LEDs activated by electrical polarity reversal or by using RGBY color type of LED emitters.
A distress red light signal of approximately 650 nm wavelength is generated by the same means of color change as in the previously described principles, a red flashing light which will automatically be triggered by the accelerometer sensors when the vehicle speed is suddenly reduced from high to a lower level or when the cruising speed is reduced below 40-45 mph.